The present invention relates to rheometers for analyzing the behavior of thin liquid films and more particularly to rheometers for measuring viscoelastic properties of liquids.
Viscoelastic properties are important in predicting how a liquid will behave under stress. Knowing these properties is becoming increasingly important as industry is starting to use polymer additives in liquid products.
Rheometers typically determine viscoelastic properties by shearing a liquid sample between plates. These surfaces are separated by a fixed gap. One plate moves relative to the other by sliding or rotating. The invention uses normal oscillations of a sample between parallel plates to determine viscoelastic properties. This approach accurately characterizes liquids with a wide range of viscosity. The technique is inherently simpler to implement at a significantly lower cost relative to prior art rheometers.